Relief valve



Nov. 22, 1938. l. l. NELSON 2,137,382

RELIEF VALVE Original Filed Deo. 1'7, 1932 Petented Nev. 2z, 193s UNITED STATI-:s` PATENT OFFICE l `Application 4 Claims.

The present invention relates to relief valves and more particularly to relief valves to be used inconnection with domestic hot Waterboilers.

The object of the invention, generally speaking, is to permit replacement of the fusibleplug in a relief valve without requiring the shut-downof the hot` water system pending and during replacement.` i A further object of the invention is to provide ina single valve the four functions of relieving on both excessive temperature and pressure within the system, vacuum within the system, and shutting 01T flow to the temperature relief meansduring replacement thereof without interference with the delivery of hot Water, from the system` or with the relieving of excessive pressures. Y

With these and other objectsin view, one feature of the invention contemplates the provision within a valve having separate temperature and pressure" relief means, of means Within the valve for temporarily shutting off'the flow of water to the temperature relief means'to permit replacement thereof, or examination, or for any other purpose. A further feature of the inven tion contemplates the provision of pressure and temperature relief means independently located with separate passages thereto and a shut-off located in the temperature relief passage to tem.- porarily cut off the supply of water thereto for replacement or other purposes.

In a simple and elcient embodiment of the invention, the valve is intended to relieve for both pressure and temperature and against vacuum, the temperature relief means being in the form of a fusible plug located in the vacuum valve which communicates with the inlet chamber through an independent passage. Located in this passage is a shut-off, which may be actuated manually to provide access to the fusible plug and vacuum valve and permit replacement. The shut-off valve is caused to yieldngly engage with its seat when closed, and may serve to relieve vacuum within the system if this should occur o during the time that the valve is normally closed.

` It will 'ce evident to those skilled in the art that access to the temperature relief member is provided to permit substitution or replacement withut dismantling the valve. It makes no difference Whether the temperature relief means is in the form of a fusible plug or some other form of vent closing and opening device actuated by excessive temperature.

Still further features of the invention consist of certain novel features of construction, com- December 17, 1932; serial No. 647,707 Renewed January 26, 1937 4 ,I

(Cl. ZTL-46) kbinations andarrangements of parts hereinafter described and claimed.` j

The invention is shown in its preferred form in the accompanying drawing, in which Fig. l is a front elevation of the relief valve, Fig. 2 is an enlarged sectional front elevation, and Fig. 3 is an enlarged sectional plan on line 3-3 of Fig. l.

The valve casing I0 is provided With'an externally threaded inlet member 'l2 by' means of which the valve may be connected to the boiler either directly or through suitable piping as desired. An inlet passage I4 connects the boiler to an inlet chamber I6. A drain pipe may be connected to an internally threaded outlet I8 which opens directly into an outlet chamber 2D. A pressure relief port 22 between the inlet and outlet chambers is normally blocked by a pres sure valve 24 acted upon by a heavy compressed spring 26, the upper end of which is secured by an adjustable abutment screw 28, loosely thread o ed into the valve casing. A threaded plug .30 serves to prevent leakage at this point.

When the pressure within the inlet chamber exceeds a certain predetermined value, the pressure valve 24 is lifted against the spring 26, and

' the inlet chamber IS is vented -through the port 22.

The inlet chamber I6 normally communicates with a by-pass chamber 32. A vacuum relief port 34 between the by-pass and outlet chambers is normally blocked by a vacuum valve 36, acted upon by a light compressed spring 38 and also by the boiler pressure. A hollow-headed screw 40 serves to compress and retain the spring 38 Aand also to seal the valve access opening 42. Upon the possible formation of a partial vacuum Within the boiler, atmospheric pressure within the outlet chamber 20 lifts the vacuum valve 36 against the pressure of the light spring 38, thus allowing air to enter the boiler, thereby relieving the vacuum.

The vacuum valve 36 is provided with an axial passage 44 which is closed by means of a tapered fusible plug 46. Should the temperature within the boiler exceed a certain predetermined value, the fusible plug `will be melted, thus venting the boiler through the axial passage 44 and the vacuum relief port 34.

Should the fusible plug 46 be melted out, fluid must be prevented from entering the by-pass chamber 32 during replacement, otherwise iflu'id r would issue from the access opening 42 upon the necessary removal of the screw 40. Therefore, an intermediate passage 48, which connects the inlet chamber I6 to the 'ny-pass chamber 32, is provided with an auxiliary valve 50 which may b rendered operative at will, and which when closed prevents fluid from entering the tay-pass chamber 32. 'Ihe auxiliary valve Il is retained in a cylindrical 'recess l2, and during normal operation of the boiler is prevented from closing an axial port 54 through a screw-threaded bush- Since overheating of the fluid in the boiler is a` condition which may be guarded against once the tendency is noted, it may be desirable to `continue operation of the boiler as soon as the temperature falls to a safe degree. Thereforerpendm ing the replacement of the` fusible plug 46, the threaded plug 60 may be partially removed. VThe auxiliary valve 50 then not only serves to prevent the waste of fluid, but also as a vacuum relief valve, and being located as it is in the intermedi ate passage, does not interfere with the operation of the pressure relief valve 24.

, What is claimed is: v

1. A relief valve comprising inlet and outlet chambers, a passage communicating between the chambers, a pressure relief valve normally closing the passage, a second passage communicating with the chambers, a vacuum relief valve in the second passage, a fusible plug mounted in the vacuum valve for relieving the occurrence of excessive temperature a second vacuum relief valve for closing the second passage and `Inanually operated means for holding the second relief valve open.

2. A relief valve comprising inlet and outlet #new " ,chambera a passage communicating between the chambers, a pressure relief valve normally clos- -ing the passage, a 'second passage communicating `with the chambers, a vacuum relief valve in the second passage, afusible plug associated with the lvacuum valve for relieving fluid pressure upon the ing thepassage, a second passage communicat- `ing with the chambers, a vacuum relief valve in the second passage, a fusible plug associated with the vacuum valve for relieving fluid pressure upon ther occurrence of excessive temperature rise, a shut-off located between the inlet chamber and vacuum valve, means for yleldingly urging the shut-off valve against its seat and manually operated means for normally retaining the shut-off valve out of engagement with its seat and to allow seating of the valve duringreplacement of the fusible plug.

4. A relief valve comprising inlet and outlet chambers, a pressure relief member normally blocking communication therebetween, a by-pass around the pressure relief member, a springloaded vacuum valve in the by-pass, a fusible member in the vacuum valve to relieve upon excessive temperature rise, a shut-off valve located in the by-pass in advance of the vacuum valve, and manually actuated means for normally retaining the shut-off valve in an inoperative position designed to permit closure of the passage by the valve during replacement of the fusible member, the shut-off valve being spring-loaded to permit vacuum relief when the valve is in operation.

IRA 1.- NELSON.y 

